1. Field of the Invention
The present invention relates to an apparatus for transmitting WPAN (Wireless Personal Area Network) MAC (Medium Access Control) frames and a method thereof, and more particularly, to an apparatus for transmitting WPAN MAC frames and a method thereof which can support asynchronous streams and isochronous streams that satisfy the IEEE Standard 802.15.3, September 2003 (hereinafter referred to as “IEEE 802.15.3”) in a WPAN environment.
2. Background of the Related Art
The WPAN MAC protocol has recently been recommended by the IEEE 802.15.3 MAC Committee as the standard for supporting asynchronous streams and isochronous streams by adopting a CSMA/CA (Carrier Sense Multiple Access/Collision Avoidance) system that considers the characteristic of a wireless medium unlike a CSMA/CD (Carrier Sense Multiple Access/Collision Detect) system used in the existing wire short-distance communication network and a TDMA (Time Division Multiple Access) system using a resource allocation algorithm.
Accordingly, the WPAN MAC frames should be stored in various corresponding transfer queues according to the traffic characteristic transferred from an upper layer, and different times and methods for the frame transmission should be applied to the frames according to respective transmission scheduling.
In order to transmit the WPAN MAC frames as described above, a MAC frame processing device for transferring the MAC frames according to the above-described characteristic between a WPAN MAC layer and a physical layer is required, and a static buffer operation method and a dynamic buffer operation method have been proposed as conventional technologies applicable to the WPAN.
The conventional static buffer operation method as described above operates buffers statically allocated by ports. Specifically, the conventional static buffer operation method allocates buffers by ports to a transport frame buffer, and sequentially reflects them in a transfer queue table to transmit the MAC frames. However, this method has the drawbacks in that since the respective ports are allocated for respective mobile terminals, many buffers are not in use but are wasted in the WPAN environment in which many mobile terminals exist.
Meanwhile, the conventional dynamic buffer operation method operates buffers dynamically allocated by ports. Specifically, the conventional dynamic buffer operation method allocates buffers to the transport frame buffer in the order of their reception, and stores them in the transfer queue table in order to transmit the MAC frames. In this case, the buffer waste can be reduced, but it is impossible to efficiently search for the frames of a specified mobile terminal.
Additionally, the above-described methods have the drawbacks in that since they store the frames in the unit of an MSDU (MAC Service Data Unit), it is impossible for them to process the frames in the unit of an MPDU (Mac Protocol Data Unit). Accordingly, they cannot support an efficient structure for a single MSDU process or an MSDU process composed of a set of MPDUs in order to support video/audio streams in the WPAN environment, and it is impossible to consider mutual collision problems caused by the memory access with the buffer waste reduced as well.